Technical Field
The present invention relates to methods of generating optical effects, and more specifically, to methods of generating lens flare effects.
Discussion of Related Art
Lens flare is caused by an undesired light reflection in an optical system. Lens flare occurs when light rays passing through the optical system are reflected towards an unintended direction by the lens surface. A lens is designed to refract incident light to reach a sensor. However, light trajectory may be changed by reflection on the interface in the lens, and even-numbered light reflections would cause the sensor to have an undesired pattern. This is called “lens flare.” A flare pattern caused by a single even-numbered reflection pattern is denoted “ghost.” Such a ghost is sensed only when there is a sufficient amount of light and the light is thus viewed by human eyes. A ghost passes through an aperture as if typical light refraction does, and it is similar in shape to the aperture.
Lens flare, although considered a defect by optics manufacturers, is observed in a picture or video in many cases, and is thought as an inevitable element for realistic imaging. A typical method of calculating a lens flare is to completely track a path along which incident light is reflected and reaches a sensor. Such a method may provide for securing of a very high-quality image, but suffers from a very large computation load on a complicated optical system. Thus, the method is hard to use in real-time. Real-time methods often used for video games or virtual reality generally employ texture sprites. In such methods, the artist manually designs and arranges flare sprites. Rendering in the methods is enough to provide a real-time performance, but consumes lots of time in designing and is complicated and difficult. Moreover, such methods take little consideration of actual physical models for lenses, causing objects to be viewed unrealistically.
Meanwhile, lens flare mostly has a linear pattern but some non-linear patterns that are considerably deformed play a critical role in reality of the lens flare. Accordingly, a need exists for techniques for generating lens flare that may include non-linear patterns as well as linear patterns in real-time applications.